Annular sealing member with enhanced hoop strength

ABSTRACT

Apparatus and method for providing a sealing member with enhanced hoop strength. In some embodiments, a valve assembly includes a piston and first means for establishing a fluid-tight seal when the piston is in a closed position and for preventing a blow out condition when the piston is transitioned to an open position. In other embodiments, a sealing member is characterized as an endless annular ring which extends about a central axis, the sealing member comprising an elongated circle cross-sectional shape while the sealing member is maintained in an uncompressed state. In other embodiments, a method comprises extruding a sealing material through an extrusion assembly to form an endless annular ring which extends about a central axis, the extrusion assembly imparting a desired amount of curvilinearity along a longitudinal length of the material to form an orthogonal seam when a leading and trailing edge of the material are adjoined.

BACKGROUND

Sealing members are used in a variety of applications to establishfluidic seals, such as in a valve assembly in a pressurized fluidsystem. Generally, it is desirable that a sealing member retain itssealing capabilities over a wide range of operational conditions. It isfurther generally desirable that a sealing member remain in place whensubjected to significant fluidic flow, such as when the sealing memberis disposed on a piston member that is moved from a closed position toan open position.

FIGS. 1A and 1B show a prior art valve assembly 10. The valve assembly10 includes a piston 12 that selectively regulates fluidic flow from aninlet port 14. The piston 12 is in a closed position in FIG. 1A. FIG. 1Billustrates the piston 12 as it transitions to an open position.

The piston 12 is sealed in the closed position using a conventionalo-ring sealing member 16. The sealing member 16 has a circularcross-sectional shape, and is retained within an annular recess 18 ofthe piston 12. An outer radial surface of the sealing member 16 forms afluidic seal against an interior annular sidewall 20 of a housing 22,and an opposing inner radial surface of the sealing member 16 forms afluidic seal against the annular recess 18.

As the piston 12 initially moves to the open position, significantamounts of fluidic flow (arrows 24) can pass adjacent the sealing member16. Particularly in higher pressure fluidic environments, a portion ofthe fluidic flow can pass between the inner radial surface of thesealing member 16 and the recess 18, exerting an outwardly directedforce upon the sealing member 16. If the hoop strength of the sealingmember 16 is insufficient to resist this outwardly directed force, thesealing member 16 may be deformed and/or dislocated (blown out) from theannular recess 18, as depicted in FIG. 1B.

SUMMARY

Accordingly, various embodiments of the present invention are generallydirected to an apparatus and method for providing a sealing member withenhanced hoop strength (i.e., ability to retain its initial hoop shape).

In accordance with some embodiments, a valve assembly is provided inwhich a piston is moved from a closed position in which a pressurizedfluidic flow is inhibited to an open position in which a pressurizedfluidic flow is established, and the improvement is characterized ascomprising first means for establishing a fluid-tight seal when thepiston is in the closed position and for preventing a blow out conditionwhen the piston is transitioned to the open position.

In accordance with other embodiments, an apparatus comprises a sealingmember characterized as an endless annular ring which extends about acentral axis, the sealing member comprising an elongated circlecross-sectional shape while the sealing member is maintained in anuncompressed state, said cross-sectional shape defined by parallel topand bottom flat surfaces of selected length L in a directionperpendicular to and intersecting the central axis and opposing innerand outer radiused surfaces of selected radius R and which respectivelyface toward and away from the central axis, wherein L is greater than R.

In accordance with yet other embodiments, a method comprises extruding asealing material through an extrusion assembly to form an endlessannular ring which extends about a central axis, the extrusion assemblyimparting a desired amount of curvilinearity along a longitudinal lengthof the material to form an orthogonal seam when a leading edge and atrailing edge of the material are adjoined.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B generally illustrate a prior art valve assembly thatutilizes a conventional o-ring with a circular cross-sectional shape toestablish a fluidic seal.

FIGS. 2A and 2B show an exemplary valve assembly incorporating a sealingmember constructed in accordance with various embodiments of the presentinvention.

FIG. 3 provides a top plan view of the sealing member of FIGS. 2A-2B.

FIG. 4 shows a cross-sectional representation of the sealing memberalong line 4-4 in FIG. 3 to illustrate an exemplary elongated circlecross-sectional shape of the member.

FIG. 5 shows respective exemplary length and radial dimensions of theelongated circle cross-sectional shape.

FIG. 6 illustrates an alternative construction for the sealing memberwhich utilizes an embedded reinforcement member.

FIG. 7 shows the use of a metal washer as the embedded reinforcementmember of FIG. 6.

FIG. 8 shows the use of a wire mesh screen as the embedded reinforcementmember of FIG. 6.

FIG. 9 shows the wire mesh screen of FIG. 8 in conjunction with anannular reinforcing ring attached thereto.

FIG. 10 illustrates a preferred manner in which the elastomeric materialof the sealing member is extruded.

FIG. 11 shows a top plan view of the extruded material after processingin accordance with FIG. 10.

FIG. 12 provides another alternative construction for the sealing memberin which a reinforcement member such as shown in FIG. 7 is attached to aselected side of the sealing member.

FIG. 13 shows an alternative extrusion process that provides sealingmembers with other cross-sectional shapes.

FIG. 14 is a cross-sectional elevational view of an alternative sealingmember configuration formed by the process of FIG. 13.

FIG. 15 is a cross-sectional elevational view of another alternativesealing member formed by the process of FIG. 13.

FIG. 16 is a side elevational, cross-sectional depiction of theextrusion mechanisms generally depicted in FIGS. 10 and 13.

FIG. 17 is an end elevational, cross-sectional depiction of theextrusion mechanism of FIG. 16.

FIG. 18 provides a flow chart for an exemplary SEALING MEMBER PROCESSINGroutine, generally illustrative of steps carried out in accordance withvarious embodiments of the present invention.

DETAILED DESCRIPTION

FIGS. 2A and 2B show relevant portions of a valve assembly 100 togenerally illustrate an exemplary environment in which variousembodiments of the present invention can be advantageously practiced.The valve assembly 100 is contemplated as being of the type configuredto selectively alter the flow of a pressurized fluid in a pressurizedfluid system, although such is not limiting.

The valve assembly 100 comprises a housing 102 with an upstream inletport 104 and a downstream outlet port 106. A piston 108 selectivelymoves between a closed position (FIG. 2A) and an open position (FIG. 2B)to selectively inhibit or permit fluidic flow of the pressurized fluidfrom the inlet port 104 to the outlet port 106. A biasing member 110,such as a spring, biases the piston 108 in the closed position. Otherbiasing arrangements can readily be used, however, or omitted entirely.

An annular sealing member 112 is disposed within a corresponding annulargroove 114 of the piston 108. The sealing member 112 contactinglyengages an annular sidewall 116 of the housing 102 to establish afluid-tight seal while the valve assembly 100 remains in the closedposition.

When the pressure of the pressurized fluid is sufficient to overcome thebiasing force supplied by biasing member 110, the piston 108 advancesupwardly as shown in FIG. 2B. As the piston 108 moves to the openposition, the sealing member 112 becomes disengaged from the sidewall116 and is subjected to the fluidic flow of the pressurized fluid as thefluid initiates passage to the outlet port 106. As explained below, thesealing member 112 is advantageously configured to provide effectivesteady-state sealing in conditions such as depicted in FIG. 1, as wellas to resist mechanical deformation and/or dislocation (blowout) whilebeing subjected to substantial amounts of fluidic flow as in FIG. 2.

FIGS. 3 and 4 provide respective top plan and cross-sectional views ofthe sealing member 112 of FIGS. 2A-2B. Generally, the sealing member 112is characterized as an endless annular ring (o-ring) which extends abouta central axis 118. The sealing member 112 is preferably formed of anelastomeric material and has a cross-sectional shape characterized as anelongated circle.

As further shown in FIG. 5, the elongated circle cross-sectional shapeof the sealing member 112 is generally defined by opposing, parallel topand bottom flat surfaces (linear segments) 120, 122, and opposing innerand outer radiused surfaces (semicircular end segments) 124, 126. Eachof the flat surfaces 120, 122 has a respective length L in a directionperpendicular to, and which intersects, the central axis 118. Each ofthe radiused surfaces 124, 126 has a respective radius R.

The cross-sectional shape represented in FIG. 5 is a steady-stateconfiguration for the sealing member 112; that is, the sealing member112 maintains the elongated circle cross-sectional shape while in anuncompressed state (i.e., in the absence of any externally appliedsupport or compression forces acting upon the member). For purposes ofclarity, it will be noted that the cross-sections of FIGS. 4 and 5 aretaken along a plane that includes the central axis 118 of the sealingmember 112.

The respective values of L and R can vary depending on the requirementsof a given application, with the length L being greater than the radiusR (L>R). Preferably, the length L is several times greater than theradius R, such as L>5*R. It is noted that the flat surfaces 120, 122 liealong respective planes normal to the central axis 118, and the radiusedsurfaces 124, 126 compressingly engage corresponding sidewalls to effectfluidic sealing at corresponding innermost diameter (ID) and outermostdiameter (OD) extents of the sealing member 112. Exemplary radial valuesR for different industry standard classes of circular cross-sectionalshaped o-rings are set forth in Table 1:

TABLE 1 CLASS RADIUS R (inches) 2-0 0.0350 2-1 0.0515 2-2 0.0695 2-30.1050 2-4 0.1375

The sealing member 112 can be adapted to have inner and outer radii thatcorrespond to any of the above classes, and used in an associatedapplication provided that the corresponding retention aperture (e.g.,114 in FIGS. 2A-2B) is extended (deepened) by a sufficient distance toaccommodate the length dimension L of the sealing member 112. It will benoted that a two-piece configuration is preferably set forth for thepiston 108 in FIGS. 2A-2B to facilitate installation of the sealingmember 112.

For reference, the sealing member 112 of FIGS. 2-4 is contemplated ascomprising an equivalent class 2-3 member, with R being nominally 0.1050inches, in (10.0060 in). The corresponding length value L of the sealingmember 112 is nominally 0.5400 in (10.0060 in). The OD of the sealingmember 112 is nominally 3.2700 in (±0.0200 in), and the ID is nominally1.9800 in (10.0160 in). The same L and R values can be used withdifferent respective ID and OD values, and vice versa, as desired.

The elongated circle cross-sectional shape has been found by the presentinventor to provide unexpected operational improvements overconventional configurations, such as the circular o-ring of FIGS. 1A-1B.The elongated circle cross-sectional shape significantly enhances hoopstrength of the sealing member 112, and the length dimension L reducesthe amount of pressure that is able to get behind the sealing member 112within the recess when the sealing member 112 is initially exposed tothe high pressure fluid.

Accordingly, the sealing member 112 maintains a fluid-tight fluidic sealin captured sealing environments (e.g., FIG. 2A), provideslow-frictional sliding contact, and is highly resistant to damage and/ordislocation in high pressure environments (e.g., FIG. 2B).

A suitable material from which the sealing member 112 can beadvantageously formed is a fluoroelastomer such as commerciallyavailable under the registered trademark Viton® by E. I. Du Pont DeNemours & Company, Wilmington, Del., USA. Other suitable materials caninclude any number of natural or synthetic rubbers, urethanes, plastics,etc. A suitable durometer (hardness) may be on the order of 70-80,depending on the requirements of a given application, although bothharder and softer materials can be used as desired. The seal membermaterial can further be filled with a suitable filler such as glassfibers, carbon filaments, nanotubes, etc.

FIG. 6 shows an alternative sealing member 132 which retains theaforedescribed elongated circle cross-sectional shape, but additionallyincorporates an internally embedded reinforcement member 134. Thereinforcement member 134 generally serves to further strengthen thesealing member 132 against damage and removal during operation, as wellas to enable the sealing member 132 to further retain its initialelongated circular shape prior to, and after, application of compressiveforces thereto.

The reinforcement member 134 of FIG. 6 can take any number of forms. Forexample, as shown in FIG. 7, a rigid washer (annular disk) 136 can beused to reinforce the sealing member 132. The washer 136 is formed of asuitably rigid material such as metal, plastic, nylon, etc.

Alternatively, the reinforcement member can comprise a wire mesh screen,such as generally depicted at 138 in FIG. 8. The screen 138 is formed ofindividual wires (filaments) arrayed in a substantially planar,cross-hatched pattern. While linear filaments are shown in FIG. 8, othershapes can be used including curvilinear filaments, as well as “out ofplane” filaments that cooperate to form a 3-dimensional latticestructure. As shown in FIG. 9, the wire mesh screen 138 of FIG. 8 canfurther be augmented with one or more reinforcing rings 140 of asuitably rigid material, such as nylon.

The sealing members 112, 132 can be formed in a number of ways. U.S.Pat. No. 6,315,299, assigned to the assignee of the present application,generally discloses a compression molded process whereby a reinforcementring is placed into an annular molding cavity. Sealing material isinjected into the cavity, such as a suitable elastomer, and thecombination is cured to form a reinforced sealing member.

While generally operable, a problem associated with the '299 patentprocess is the inability to consistently maintain the reinforcement ringwithin a centrally disposed orientation of the sealing material. Often,the injected material deflects the ring and pushes it to one side of theannular cavity, resulting in nonuniform thicknesses of elastomericmaterial coverage, or even exposure of the ring through the curedsealing member.

Accordingly, various embodiments presented herein preferably form thesealing member using an extrusion process, such as set forth by FIG. 10.An extrusion mechanism 142 extrudes uncured seal material 144 so thatthe extruded material remains in a soft, malleable state. A guide 146 atthe exit portion of the mechanism 142 preferably induces a desiredamount of curvilinearity to the extruded material 144 along alongitudinal length thereof as it exits the mechanism 142 to provide asubstantially circular shape.

As depicted in FIG. 11, this advantageously forms an orthogonal matingseam 148 between the leading edge and the trailing edge of the extrudedmaterial 144; that is, the leading and trailing edges nominally align atthe seam (unction) 148, ensuring substantially uniform thickness andeliminating voids or other discontinuities in the sealing material. Itis contemplated that the seam 148 will remain visible in the sealingmember at the conclusion of the subsequent curing process withoutaffecting the operation thereof, and will enhance the hoop strength atthe seam by facilitating improved joining of the respective edges.

When an internal reinforcement member as shown in FIGS. 6-9 is to beincorporated into the sealing member, the extruded material 144 ispreferably hollow; that is, as shown in FIG. 10, a central channel, orinterior aperture 150 will extend through the extruded material 144 asit exits the extrusion mechanism 142. A slit can be subsequently formedin the extruded material 144 at the ID thereof to facilitate placementof the reinforcement member 134 therein.

Alternatively, as shown in FIG. 10 an extruded slit 152 can be formeddirectly in the extruded material 144 during the extrusion process,facilitating subsequent insertion of the reinforcement member 134. Ineither case, the extruded material 144 is thereafter cured in a suitablecuring operation to form the final sealing member.

FIG. 12 shows another alternative embodiment for a sealing member,numerically denoted therein at 162. The sealing member 162 includes anelastomeric material with an elongated circle cross-sectional shape asbefore. An externally disposed reinforcement member 164 is affixed to aselected side of the elastomeric material, in this case the bottom flatsurface 122. The reinforcement member 164 in FIG. 12 is generally diskshaped, similar to the washer configuration previously set forth in FIG.7. However, such is not limiting in that any number of alternativeconfigurations for the externally disposed reinforcement member 164 canbe used including, but not limited to, the screen-based configurationsof FIGS. 8-9.

While various embodiments presented above provided a sealing member withenhanced hoop strength in conjunction with the provision of an elongatedcircle cross-sectional shape, other embodiments disclosed herein areprovided with alternative cross-sectional shapes. FIG. 13 illustrates analternative extrusion process generally similar to that previously setforth in FIG. 10.

The process of FIG. 13 preferably uses an extrusion mechanism 166 andguide 168 to provide curvilinearly extending, uncured extruded material170 that mates at an orthogonal seam 148, as before (FIG. 11). However,the extruded material 170 in FIG. 13 is provided with a substantiallycircular cross-sectional shape, unlike the elongated circle shape formedin FIG. 10.

An interior aperture 172 is formed in the material 170 to accommodatethe insertion of a suitable reinforcement member 174, such as an annularnylon ring as shown in FIG. 14. The formation of the interior aperture172 during the extrusion process substantially ensures that thereinforcement member 174 will be maintained within the extruded material170 with a uniform thickness of the material 170 surrounding the member174.

As desired, a slit can be cut at the ID of the material 170 tofacilitate insertion of the member 174, or an extruded slit 176 can beformed during the extrusion process (FIG. 13). It is contemplated thatthe existence of the slit will remain observable upon curing of thesealing member.

Because the extrusion process precisely locates the centrally disposedaperture 172, any number of cross-sectional shapes can be employed inthe extruded material 170, such as an exemplary rounded rectanglecross-sectional shape as shown in FIG. 15.

FIGS. 16-17 further illustrate preferred aspects of the variousextrusion processes disclosed herein. For clarity, FIGS. 16-17 areillustrated with respect to the extrusion process of FIG. 10, althoughit will be understood that these figures can readily be adapted to theprocess of FIG. 13.

In FIG. 16, a housing 178 defines an interior sidewall 180 with a shapenominally conforming to the desired cross-sectional shape of theextruded material (144 in FIG. 10). A cantilevered, centrally disposedbarrier portion 182 is supported by a support arm 184 to form theinterior aperture 150 in the extruded material. As desired, the interiorsidewall 180 can include a curvilinearly shaped exit portion 186 toinitiate the desired curvilinearity along the longitudinal length of theextruded material 144, with or without the further use of the externalguide 146.

FIG. 17 generally provides an end view of the arrangement of FIG. 16. Adiverting flange 188 extends from the barrier portion 182 in a directionsubstantially orthogonal to the support arm 184 (FIG. 16). The flange188 further interrupts the flow of the extruded material 144 to form theaforementioned slit 152 (FIG. 10).

FIG. 12 provides a flow chart for a SEALING MEMBER PROCESSING routine200, generally illustrative of preferred steps carried out in accordancewith the foregoing discussion.

At step 202, a suitable sealing material is initially extruded from asuitable extrusion process such as depicted in FIGS. 10, 13 and 16-17.The extruded material (such as 144) is preferably in an uncured statesuch as an uncured elastomeric material. The extrusion process furtherpreferably imparts a desired level of curvilinearity to the extrudedmaterial 144 as it exits the extrusion process, thereby ensuring anorthogonal mating seam (148, FIG. 11).

When an interiorly placed reinforcement member is desired, the extrudedmaterial is supplied with an extruded central aperture, such as 150 inFIG. 10 or 172 in FIG. 13. In such case a slit is additionally formed atstep 204 in the extruded material. This can be carried out by a separateslitting operation, or by extruding the slit into the extruded material144 (FIG. 17). The interiorly placed reinforcement member is theninserted at step 206 into the central aperture.

Alternatively, when an exteriorly placed reinforcement member isdesired, the reinforcement member is attached directly to an appropriateouter surface of the member at step 206. It will be noted that urethaneexhibits adhesive properties when cured, so that the use of urethane asthe extruded material may not necessarily require the use of a separatebonding agent (adhesive, etc.) to adhere the reinforcement member to theextruded material.

The material is next cured in a suitable curing operation at step 208.This preferably involves placing the material into a molding cavity andsubjecting the material to selected pressure and/or temperature levelsfor a suitable dwell time associated with the material to effect thecuring process. Other arrangements, such as curing ovens, can readily beused, however.

As shown by step 210, the cured sealing member is thereafter removedfrom the molding operation and used in an appropriate application toeffect a fluidic seal, such as in a valve member as depicted in FIGS.2A-2B. The process then ends at step 212.

For purposes of the appended claims, the recited first means will beunderstood to correspond to the aforedescribed sealing members thatachieve enhanced hoop strength, namely the elongated circlecross-sectional shaped sealing member 112 of FIGS. 2A-2B, 3-5; theelongated circle cross-sectional shaped sealing member 132 with anassociated internally disposed reinforcement member 134-140 of FIGS.6-9; the elongated circle cross-sectional shaped sealing member 162 withexternally disposed reinforcement member 164 of FIG. 12; and theextruded sealing members with respective circular and rounded rectanglecross-sectional shapes and interiorly placed reinforcement members ofFIGS. 14-15. Prior art conventional o-rings as discussed in FIGS. 1A-1B,and prior art reinforced o-rings with molded in place reinforcementrings as disclosed by the aforementioned '299 patent process, are notincluded within the scope of the recited first means and are explicitlyexcluded from the definition of an equivalent.

Moreover, for purposes of the appended claims the term “elongatedcircle” will be understood to correspond to a shape such as set forth inFIG. 5 in which a circle is linearly extended in a single direction(i.e., opposing 180 degree semicircular segments separated by linearline segments), and will thus exclude continuously curvilinear shapessuch as ellipses and ovals, as well as segmented shapes such as arounded rectangle.

It is to be understood that even though numerous characteristics andadvantages of various embodiments of the present invention have been setforth in the foregoing description, together with details of thestructure and function of various embodiments of the invention, thisdetailed description is illustrative only, and changes may be made indetail, especially in matters of structure and arrangements of partswithin the principles of the present invention to the full extentindicated by the broad general meaning of the terms in which theappended claims are expressed.

1. In a valve assembly in which a piston is moved from a closed positionin which a pressurized fluidic flow is inhibited to an open position inwhich a pressurized fluidic flow is established, the improvementcharacterized as comprising first means for establishing a fluid-tightseal when the piston is in the closed position and for preventing a blowout condition when the piston is transitioned to the open position. 2.The improvement of claim 1, wherein the first means comprises an annularsealing member characterized as an o-ring with an elongated circlecross-sectional shape while the sealing member is in an uncompressedstate, the cross-sectional shape taken along a plane that includes acentral axis of the sealing member and defined by opposing inner andouter semicircular end surface segments of a selected radius R, andopposing top and bottom linear surface segments therebetween of aselected length L greater than R.
 3. The improvement of claim 2, whereinthe sealing member further comprises an elastomeric material and anannular reinforcement member affixed to the elastomeric material.
 4. Theimprovement of claim 3, wherein the annular reinforcement member isdisposed within an annular interior aperture of the elastomericmaterial.
 5. The improvement of claim 3, wherein the annularreinforcement member is affixed to an outermost top or bottom surface ofthe elastomeric material.
 6. The improvement of claim 1, wherein thefirst means comprises a sealing member formed of extruded material withan induced curvilinear longitudinal shape to form an orthogonal seamwhen a leading edge and a trailing edge of the extruded material areadjoined.
 7. The improvement of claim 6, wherein the extruded materialfurther comprises a central aperture that is extruded in the extrudedmaterial.
 8. The improvement of claim 7, wherein the extruded materialfurther comprises a slit that is extruded in the extruded material at aninnermost diameter of the sealing member, the slit and central apertureaccommodating placement of an interiorly placed reinforcement memberinto the extruded material.
 9. The improvement of claim 1, wherein thefirst means comprises an extruded sealing member with an interiorlyplaced annular reinforcement member inserted through a slit at aninnermost diameter of the sealing member.
 10. An apparatus comprising asealing member characterized as an endless annular ring which extendsabout a central axis, the sealing member comprising an elongated circlecross-sectional shape while the sealing member is maintained in anuncompressed state, said cross-sectional shape defined by parallel topand bottom flat surfaces of selected length L in a directionperpendicular to and intersecting the central axis and opposing innerand outer radiused surfaces of selected radius R and which respectivelyface toward and away from the central axis, wherein L is greater than R.11. The apparatus of claim 10, wherein the sealing member is formed ofan elastomeric material.
 12. The apparatus of claim 11, wherein thesealing member further comprises a rigid annular reinforcement memberaffixed to the elastomeric material.
 13. The apparatus of claim 12,wherein the reinforcement member is embedded within the elastomericmaterial so that the elastomeric material wholly surrounds thereinforcement member.
 14. The apparatus of claim 12, wherein thereinforcement member is affixed to a selected one of the top or bottomfiat surfaces of three sealing member.
 15. The apparatus of claim 10,wherein the sealing member further comprises an annular reinforcementmember characterized as a rigid washer.
 16. The apparatus of claim 10,wherein the sealing member further comprises an annular reinforcementmember characterized as a wire mesh screen.
 17. The apparatus of claim I0, wherein the annular reinforcement member further comprises at leastone rigid annular ring affixed to the wire mesh screen.
 18. Theapparatus of claim 10, wherein L is greater than 5*R.
 19. The apparatusof claim 10, further comprising a valve member comprising an annulargroove in which the sealing member is disposed so that the outerradiused surface of the sealing member contactingly engages an interiorannular sidewall to effect a first fluidic seal and the inner radiusedsurface of the sealing member contactingly engages the annular groove toeffect a second fluidic seal, wherein said elongated circlecross-sectional shape of the sealing member facilitates retention of thesealing member within the groove.
 20. A method comprising a step ofextruding a sealing material through an extrusion assembly to form anendless annular ring which extends about a central axis, the extrusionassembly imparting a desired amount of curvilinearity along alongitudinal length of the material to form an orthogonal seam when aleading edge and a trailing edge of the material are adjoined.
 21. Themethod of claim 21, further comprising a step of curing the material toform a cured sealing member configured to establish a fluidic seal. 22.The method of claim 20, wherein the extruding step further comprisesextruding a central aperture in the material along the longitudinallength thereof.
 23. The method of claim 22, further comprising a step ofinserting an annular reinforcement member into the central aperturethrough a slit formed through the material.
 24. The method of claim 22,wherein the extruding step further comprises extruding a slit along thelongitudinal length of the material in communication with the centralaperture.
 25. The method of claim 24, further comprising inserting anannular reinforcement member into the central aperture through theextruded slit.
 26. The method of claim 20, wherein the extruded materialis provided with an elongated circle cross-sectional shape while thematerial is in an uncompressed state, the cross-sectional shape takenalong a plane that includes the central axis and defined by opposinginner and outer semicircular end surface segments of a selected radiusR, and opposing top and bottom linear surface segments therebetween of aselected length L greater than R.
 27. The method of claim 26, wherein Lis greater than 5*R.